Title of Invention

PROCESS FOR IMPROVING THE STRENGTH OF STEEL DRUM

Abstract

A process for improving the strength of steel drum, provided with top dished end cover with filling openings and bottom dished end cover without opening having steps of- a. Selecting length of the steel sheet to form drum shell less than desired diameter, b. Forming the cylindrical drum shell of the said steel sheet by resistance welding along longitudinally over the lapping joint; c. Cold expanding the said shell by means of segmented expander with steadily increasing the expansion force throughout the length beyond elastic limit; d. Forming the corrugation to the said steel shell one at a time; and e. The said top and bottom dished end covers fitted by twisting together flanges of the said shell and dished end cover together forming double or triple seam joint

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (Section 10) PROCESS FOR IMPROVING THE STRENGTH OF STEEL DRUM BALB1R ON KAR SINGH 21,DHARAMJYOT, A.B.N AIR ROAD, JUHU, MUMBAI-400049 MAHARASTRA,INDIA INDIAN THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:- ORIGINAL 431/MUM/2004 TECHNICAL FIELD This invention relates to the process for improving the strength of a steel drum. More particularly increasing the strength of the steel drum while decreasing the weight of steel required to manufacture the drum of the same dimensions and packing capacity. BACKGROUND OF INVENTION A steel drum has three components. a. The body, (1) which is a cylindrical shell, made of steel sheet and has rolling hoops (2) and corrugations (3) b. The top dished ends with opening for filling. c. Bottom dished ends. These components are assembled by fixing top dished ends and bottom dished ends on both side of the cylindrical body shell by round seaming. The steel consumption for making the body of the drum is around 2/3rd of the total steel required for fabricating a drum. For reduction in the weight of the steel required to fabricate a drum, the body weight is therefore important factor while considering reduction in steel consumption of a drum. A steel drum is made of steel sheet, thickness of which is decided as accepted in the market and standardized to suit it's dimensions, packing capacity and the strength required to withstand the transporting and decanting hazards it has to face while being used for packing a particular material. There is always a pressure from user market to reduce the packing cost per unit of material packed for the same size of drum. This can be done only by reducing the weight of steel required which in torn is possible by downgaughig the steel used for its consumption. The drawback is that as a gauge of a steel used is lowered the strength of the body is reduced. This invention relates to the method by which strength of the body shell is increased after lowering the gauge of steel normally used for making the drum body. OBJECTIVE OF INVENTION The main objective of the invention is to reduce the weight of the steel required to fabricate the body of the drum of the size required with increased strength which 2 otherwise gets reduced because of thinner steel sheet used. By doing this the objective of reduction in the cost of packing per unit of material packed is achieved. INVENTION SUMMARY Accordingly present invention provides a process for improving the strength of steel drum, provided with top dished end cover with filling openings and bottom dished end cover without opening having steps of> a. Selecting length of the steel sheet to form drum shell less than desired diameter, b. Forming the cylindrical drum shell of the sard steel sheet by resistance welding along longitudinally over the lapping joint; c. Cold expanding the said shell by means of segmented expander with steadily increasing the expansion force throughout the length beyond elastic limit; d. Forming the corrugation to the said steel shell one at a time; and e. The said top and bottom dished end covers fitted by twisting together flanges of the said shell and dished end cover together forming double or triple seam joint BRIEF DESCRIPTION OF DRAWINGS Attached toted drawings three sheets. Fig I- shows the Cross section of drum body shell showing corrugation (3), beeds (2) and flanges (4) on the body. Fig 2- Showing corrugation method presently being used on drum body shell sheet being rolled between two disc rollers under pressure to form all the corrugation simultaneously. Fig 3- Shows the pressure point in this process coming into play during the rolling process which stretch the sheet as adjacent areas are also under pressure. This causes the sheet being stretched between two corrugations thereby reducing its thickness between a crest and vally of corrugation. (Fig 4) This is because extra sheet length required for formation of the hump cannot flow from the adjacent side as adjacent corrugation being formed are holding the sheet firmly under pressure. This restricts movement of extra sheet length required from the hump which is compensated by stretching in between the pressure points thereby reducing its thickness in this case the length of shell remains same in the process. 3 Fig 5- Shows die cylindrical shell (1) of the body of die drum made with smaller diameter and is cold expanded uniformly and radially to achieve the final diameter required. This is done wim segmented expanders of die same length as of die drum body shell as shown. Fig 6 - Showing invented method of corrugating one at a time with pressure points to form single corrugation at one time. Showing sheet flow from the side of the shell to accommodate die extra lengdi required to form the hump. In tins case die lengdi of die shell reduces as one corrugation is formed at a time. DETAIL DESCRIPTION OF PROCESS There are two steps in die process. Step 1- The making of diameter of die drum body shell. The body of die drum is made out of steel sheet die widm of which relates to the height and lengdi to die diameter of die drum. The sheet is round formed to die desired diameter. The ends of diis sheet are resistance welded longitudinally wim a overlap joint To form a cylinder die lengdi of die sheet is calculated as follows. 3.1415 x D + Overlap widm required for resistance welding. Where D is Mean diameter of die shell in millimeter = Internal diameter of the drum in Millimeter + One tiiickness of die steel sheet in Millimeter In die new process die cylinder of die drum body D is made smaller by reducing die length of die sheet The shell of smaller diameter is thus cold expanded steadily, radially, uniformly throughout its length of die shell. By diis process apart from reduction of steel requirement die toughness of drum body increases because of cold stretching of die body sheet This cold outward expansion of die body shell steel is done by a segmented expander and increasing die expansion force uiroughout die lengdi of die body steadily beyoikl elastic limits. This force applied is more dian die critical point where die sheet begins to yield will simultaneously drop in die stress required to continue die deformation. This plastic deformation of steel sheet results in strain hardening and is 4 accompanied by change in both internal and external state of the steel and is not reversible. It involves distortion of crystal and microstructure of steel sheet thereby improving the mechanical properties of the sheet This increases a. The ultimate tensile strength of the steel sheets. b. The yield strength of the steel sheets. c. The hardness of the steel sheets. d. The fatigue strength of the steel sheets, e The wear resistance of the steel sheets. This also improves the surface finish of sheet. By mis process apart from the reduction of steel required to make a body shell of the drum, the strength of the body shell improves substantially as above. Step 2- The method by which the corrugation on the body of the drum are formed. Presently in the corrugation operation for forming the corrugation (3) on the drum body all corrugation are formed together by rolling the cylinder of body shell sheet between two set of rotating disc rollers under pressure from both sides. Fig 2 shows the number of disc rollers being equal to the number of corrugation required. In this process the shell sheet is stretched during formation of corrugation thereby reducing the length on both sides of the shell. In the invented process the corrugation (3) on the body shell (I) are formed, one at a time rather than all at a time (Fig 6). Forming all corrugation together, which results in stretching the sheet to compensate for the extra length needed to form the crest of the corrugation. This stretching thinning down the sheet making it a weaker area on the drum body. By forming one corrugation at a time there will be no stretching and sheet thickness will remain same throughout This would allow the extra length of sheet required to form the crest of one corrugation flow from side, reducing the length of the shell to that extent The combined effect of modification in the above two processes results in a tougher body shell of uniform thickness throughout its length, which otherwise is not possible with the present methods on practice. 5 I Claim 1 A process for improving the strength of steel drum, provided with top dished end cover with filling openings and bottom dished end cover without opening having steps of- a. Selecting length of the steel sheet to form drum shell less than desired diameter, b. Forming the cylindrical drum shell of the said steel sheet by resistance welding along longitudinally over the lapping joint; c. Cold expanding the said shell by means of segmented expander with steadily increasing the expansion force throughout the length beyond elastic limit; d. Forming the corrugation to the said steel shell one at a time; and e. The said top and bottom dished end covers fitted by twisting together flanges of the said shell and dished end cover together forming double or triple seam joint 2 A process as claimed in claim I wherein the increase in diameter due said cold expansion is 1/10th of the said shell diameter. 3 A process for improving the strength of steel drum substantially as herein described with reference to the figures of accompanying drawing. Dated 21st day of April 2004 (BALBIR ONKAR SINGH) 6

Documents:

431-mum-2004-cancelled pages(23-06-2004).pdf

431-mum-2004-claims(granted)-(23-06-2004).doc

431-mum-2004-claims(granted)-(23-06-2004).pdf

431-mum-2004-correspondence(23-06-2004).pdf

431-mum-2004-correspondence(ipo)-(04-08-2004).pdf

431-mum-2004-drawing(23-06-2004).pdf

431-mum-2004-form 1(23-06-2004).pdf

431-mum-2004-form 19(08-04-2004).pdf

431-mum-2004-form 2(granted)-(23-06-2004).doc

431-mum-2004-form 2(granted)-(23-06-2004).pdf

431-mum-2004-form 5(22-04-2004).pdf

431-mum-2004-other document(08-04-2004).pdf

abstract1.jpg